Early Hominins (Ardipithecus) and Australopithecines
Answer the following questions based on the Canvas reading, the websites, and the video. You must provide detailed answers to each question for full credit. Try your best to summarize the information and write what you have learned in your own words. Any text that you directly copy needs to be in quotation marks
Please re-copy each number of your answers to correspond with the question numbers. Answer in full sentences and make sure to DESCRIBE when asked to do so.
From the Canvas Pages and Web Links:
1. What is a hominin, and when did the hominin lineage originate? What are the two characteristics that are used to identify hominin fossils?
2. a) Describe the significance of reduced canine size in hominins b) Compare the image of the human and chimpanzee skeletons, and read over the skeletal differences between the two species. Describe the differences that you think are most obvious between the human and chimpanzee skeletons.
4. Describe the general characteristics of the “Early Hominins” (Ardipithecus group) and what is known about the “Ardi” skeleton.
5. Describe the general characteristics of the “Australopithecus” group and what is known about the Lucy skeleton. What were the major differences between Australopithecus and Paranthropus, and what is the reason that they were able to co-exist?
From the short film “Great Transitions: The Origins of Humans.”
6. Why did the Leakeys decide to look for hominin fossils in Africa? What evidence suggests that more than one hominin species was living in Africa 1.8 million years ago?
7. Besides bones, what other evidence is there to suggest that Australopithecus was bipedal? Which evolved first among hominins: tool use or bipedality, and how do we know?
8. What evidence suggests that Ardi could climb well? What does Dr. White mean when he calls Ardi a mosaic?
9. What evidence did Dr. Whites team collect that suggests Ardi lived in a woodland?
10. What does Dr. White mean when he says that members of the genus Homo are technological primates?
You will be graded using the following rubric:
Grading Rubric
A 90-100% Outstanding work with thorough, detailed, and clearly written answers
Reading: Hominin Characteristics
https://www.biointeractive.org/classroom-resources/human-origins
http://efossils.org/book/anatomical-evidence-bipedalism
http://efossils.org/book/why-bipedalism
https://humanorigins.si.edu/evidence/human-family-tree
Reading: Early Hominins (Ardipithecus group)
The fossil record from 7-4 ma consists of 4 species: Sahelanthropus tchadensis, Orrorin tugenensis, Ardipithecus kadabba, and Ardipithecus ramidus. Together these species form a group called the “Early Hominins”, though we have the most knowledge about Aridipithecus ramidus, so sometimes this group is called “Ardipithecus” (as in the image below). Sahelanthropus is from the country of Chad (North-Central Africa), while the other three species are from Ethiopia (East Africa).
These species show some evidence of reduced canine size and bipedalism (which is why they are on the hominin family tree), but overall they still look very primitive (meaning, similar to the ancestor of humans and chimps/bonobos). You can read more about each species here:
Sahelanthropus tchadensis: https://humanorigins.si.edu/evidence/human-fossils/species/sahelanthropus-tchadensis
Orrorin tugenensis: https://humanorigins.si.edu/evidence/human-fossils/species/orrorin-tugenensis
Ardipithecus kadabba: https://humanorigins.si.edu/evidence/human-fossils/species/ardipithecus-kadabba
Ardipithecus ramidus: https://humanorigins.si.edu/evidence/human-fossils/species/ardipithecus-ramidus
Hominin family tree with the Ardipithecus group highlighted.
[image from http://humanorigins.si.edu/evidence/human-family-tree ]
Fossils of Ardipithecus ramidus are found in Ethiopia and date to 4.4 ma. A partial skeleton nicknamed “Ardi” tells us that Ardipithecus had a small brain size and a small body size. Some parts of the skeleton were adapted to climbing trees, but Ardi also had a reduced canine size and some evidence of bipedal traits. Read more about Ardi here: http://humanorigins.si.edu/evidence/human-fossils/fossils/ara-vp-6500
and see the Ardi skeleton, along with a reconstruction, below.
Ardi skeleton and reconstruction
[image from: Boisserie Jean-Renaud. Ardipithecus ramidus and the birth of humanity. In: Annales d’Ethiopie. Volume 25, anne 2010. pp. 271-281]
reading: Australopithecines (Australopithecus and Paranthropus groups)
From 4-1 ma there were two types of hominins: the “Australopithecus group” and the “Paranthropus group”. Most of these fossils are found in East Africa (Ethiopia, Kenya, and Tanzania) and South Africa. These species had smaller canine sizes and were better bipeds than the Early Hominin group. Otherwise, they still looked a lot like their chimp/human ancestor (small body size, small brain size, projecting face).
Have you every heard of the famous “Lucy” skeleton? At the time of its discovery (1974), it was the oldest known hominin skeleton (dated to 3.2 ma). [NOTE: Now the Ardi skeleton is the oldest.] Lucy belongs to the species Australopithecus afarensis. Read more about the Lucy skeleton here: http://humanorigins.si.edu/evidence/human-fossils/fossils/al-288-1
“Australopithecus” group
There are many species in the Australopithecus group, but two species in particular have been extensively studied: Australopithecus afarensis from East Africa and Australopithecus africanus from South Africa. Read about these important species here:
Australopithecus afarensis: https://humanorigins.si.edu/evidence/human-fossils/species/australopithecus-afarensis
Australopithecus africanus: https://humanorigins.si.edu/evidence/human-fossils/species/australopithecus-africanus
Hominin family tree with the Australopithecus group highlighted
[image from http://humanorigins.si.edu/evidence/human-family-tree ]
“Paranthropus” group
At the same time as the Australopith group existed, there were other hominins that were different enough to be placed into their own genus (Paranthropus). These hominins resembled Australopithecus from the neck down, but had huge skulls and teeth! This is because they ate really hard foods, such as nuts and tough vegetation. Eating different foods than Australopithecus allowed these two groups to co-exist, rather than compete with each other.
Read more about one particular Paranthropus species (Paranthropus boisei) here:
https://humanorigins.si.edu/evidence/human-fossils/species/paranthropus-boisei
Hominin family tree with the Paranthropus group highlighted
[image from http://humanorigins.si.edu/evidence/human-family-tree ]
From the short film “Great Transitions: The Origins of Humans.”
https://www.youtube.com/watch?v=Yjr0R0jgct4
